Use a smarter algorithm to filter out backlog messages
Use a smarter algorithm to filter out backlog messages

Now the runner doesn't check every message if they're from the
backlog at the start of the bot, but it tries to bulk check them in a
smarter way. This increases performances a lot if you've big backlogs.

thesharp/botogram,pietroalbini/botogram,pietroalbini/botogram,thesharp/botogram